On a Nodemcu, Is it possible to add a drop-down box to the html wifi setup page?

Hi,
I am using a Nodemcu with standard WiFi manager code as listed below.

Is it possible to add a drop-down box to the html wifi setup page where user selects something from a list and that selection is saved to NV ram (like the wifi connection details are) and be accessible to code when connected to the router after a reboot?

Example

On WiFi Setup html Page:

  • Set Wifi Password
  • Dropdown box listing 10, 20, 30, 40, user selects '30'

Then Nodemcu reboots and connects to wifi as specified in setup
Variable x now = 30 and can be used in a script.

I just dont know how to go about coding this...

Thanks

/*********
  Rui Santos
  Complete project details at http://randomnerdtutorials.com  
*********/

#include <ESP8266WiFi.h>
#include <DNSServer.h>
#include <ESP8266WebServer.h>
#include <WiFiManager.h>         // https://github.com/tzapu/WiFiManager

// Set web server port number to 80
WiFiServer server(80);

// Variable to store the HTTP request
String header;

// Auxiliar variables to store the current output state
String output5State = "off";
String output4State = "off";

// Assign output variables to GPIO pins
const int output5 = 5;
const int output4 = 4;

void setup() {
  Serial.begin(115200);
  
  // Initialize the output variables as outputs
  pinMode(output5, OUTPUT);
  pinMode(output4, OUTPUT);
  // Set outputs to LOW
  digitalWrite(output5, LOW);
  digitalWrite(output4, LOW);

  // WiFiManager
  // Local intialization. Once its business is done, there is no need to keep it around
  WiFiManager wifiManager;
  
  // Uncomment and run it once, if you want to erase all the stored information
  //wifiManager.resetSettings();
  
  // set custom ip for portal
  //wifiManager.setAPConfig(IPAddress(10,0,1,1), IPAddress(10,0,1,1), IPAddress(255,255,255,0));

  // fetches ssid and pass from eeprom and tries to connect
  // if it does not connect it starts an access point with the specified name
  // here  "AutoConnectAP"
  // and goes into a blocking loop awaiting configuration
  wifiManager.autoConnect("Bazooka");
  // wifiManager.autoConnect("AutoConnectAP");
  // or use this for auto generated name ESP + ChipID
  //wifiManager.autoConnect();
  
  // if you get here you have connected to the WiFi
  Serial.println("Connected.");
  
  server.begin();
}

void loop(){
  WiFiClient client = server.available();   // Listen for incoming clients

  if (client) {                             // If a new client connects,
    Serial.println("New Client.");          // print a message out in the serial port
    String currentLine = "";                // make a String to hold incoming data from the client
    while (client.connected()) {            // loop while the client's connected
      if (client.available()) {             // if there's bytes to read from the client,
        char c = client.read();             // read a byte, then
        Serial.write(c);                    // print it out the serial monitor
        header += c;
        if (c == '\n') {                    // if the byte is a newline character
          // if the current line is blank, you got two newline characters in a row.
          // that's the end of the client HTTP request, so send a response:
          if (currentLine.length() == 0) {
            // HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
            // and a content-type so the client knows what's coming, then a blank line:
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println("Connection: close");
            client.println();
            
            // turns the GPIOs on and off
            if (header.indexOf("GET /5/on") >= 0) {
              Serial.println("GPIO 5 on");
              output5State = "on";
              digitalWrite(output5, HIGH);
            } else if (header.indexOf("GET /5/off") >= 0) {
              Serial.println("GPIO 5 off");
              output5State = "off";
              digitalWrite(output5, LOW);
            } else if (header.indexOf("GET /4/on") >= 0) {
              Serial.println("GPIO 4 on");
              output4State = "on";
              digitalWrite(output4, HIGH);
            } else if (header.indexOf("GET /4/off") >= 0) {
              Serial.println("GPIO 4 off");
              output4State = "off";
              digitalWrite(output4, LOW);
            }
            
            // Display the HTML web page
            client.println("<!DOCTYPE html><html>");
            client.println("<head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">");
            client.println("<link rel=\"icon\" href=\"data:,\">");
            // CSS to style the on/off buttons 
            // Feel free to change the background-color and font-size attributes to fit your preferences
            client.println("<style>html { font-family: Helvetica; display: inline-block; margin: 0px auto; text-align: center;}");
            client.println(".button { background-color: #195B6A; border: none; color: white; padding: 16px 40px;");
            client.println("text-decoration: none; font-size: 30px; margin: 2px; cursor: pointer;}");
            client.println(".button2 {background-color: #77878A;}</style></head>");
            
            // Web Page Heading
            client.println("<body><h1>ESP8266 Web Server</h1>");
            
            // Display current state, and ON/OFF buttons for GPIO 5  
            client.println("<p>GPIO 5 - State " + output5State + "</p>");
            // If the output5State is off, it displays the ON button       
            if (output5State=="off") {
              client.println("<p><a href=\"/5/on\"><button class=\"button\">ON</button></a></p>");
            } else {
              client.println("<p><a href=\"/5/off\"><button class=\"button button2\">OFF</button></a></p>");
            } 
               
            // Display current state, and ON/OFF buttons for GPIO 4  
            client.println("<p>GPIO 4 - State " + output4State + "</p>");
            // If the output4State is off, it displays the ON button       
            if (output4State=="off") {
              client.println("<p><a href=\"/4/on\"><button class=\"button\">ON</button></a></p>");
            } else {
              client.println("<p><a href=\"/4/off\"><button class=\"button button2\">OFF</button></a></p>");
            }
            client.println("</body></html>");
            
            // The HTTP response ends with another blank line
            client.println();
            // Break out of the while loop
            break;
          } else { // if you got a newline, then clear currentLine
            currentLine = "";
          }
        } else if (c != '\r') {  // if you got anything else but a carriage return character,
          currentLine += c;      // add it to the end of the currentLine
        }
      }
    }
    // Clear the header variable
    header = "";
    // Close the connection
    client.stop();
    Serial.println("Client disconnected.");
    Serial.println("");
  }
}

I think that do do exactly what you describe, you would need to modify the WiFi Manager library, which would require advanced knowledge and experience.

Can you please explain why you want to do this? I think this could be an "X-Y" problem.

I am building a crypto price ticker display but rather than hard coding the coin api url I want to be able to select it from a list of multiple coin options the wifi setup page.

I added it in this project, but it is complicated.

Ok, I get it.

You could have the nodeMCU host a simple web page which can be accessed from your local lan where the coin can be selected. The selection could be stored in eeprom (which is emulated using flash memory on esp8266) so that the selection is not lost if power is disconnected. Your sketch above already hosts a web page, which allows gpio pins to be controlled, so that could be extended to include the coin selection drop-down. The least user-friendly aspect of this for a non-technical user is knowing what IP address to connect to, but you have a display, so you could use that to guide the user, enabling them to access the page and select the coin option.

Can you explain what this is?

Yes this is the plan, what i am asking is does anyone know where to start with coding these mod's to the library? I found the string_en.h file contains the html wifi setup page code so I assume I would add the code to display the drop-down box here but not sure how to save the result to the eeprom.

strings_en.h

/**
 * strings_en.h
 * engligh strings for
 * WiFiManager, a library for the ESP8266/Arduino platform
 * for configuration of WiFi credentials using a Captive Portal
 * 
 * @author Creator tzapu
 * @author tablatronix
 * @version 0.0.0
 * @license MIT
 */

#ifndef _WM_STRINGS_H_
#define _WM_STRINGS_H_

#ifndef WIFI_MANAGER_OVERRIDE_STRINGS
// !!! ABOVE WILL NOT WORK if you define in your sketch, must be build flag, if anyone one knows how to order includes to be able to do this it would be neat.. I have seen it done..

const char HTTP_HEAD_START[]       PROGMEM = "<!DOCTYPE html>"
"<html lang='en'><head>"
"<meta name='format-detection' content='telephone=no'>"
"<meta charset='UTF-8'>"
"<meta  name='viewport' content='width=device-width,initial-scale=1,user-scalable=no'/>"
"<title>{v}</title>";

const char HTTP_SCRIPT[]           PROGMEM = "<script>function c(l){"
"document.getElementById('s').value=l.innerText||l.textContent;"
"p = l.nextElementSibling.classList.contains('l');"
"document.getElementById('p').disabled = !p;"
"if(p)document.getElementById('p').focus();}</script>"; // @todo add button states, disable on click , show ack , spinner etc

const char HTTP_HEAD_END[]         PROGMEM = "</head><body class='{c}'><div class='wrap'>"; // {c} = _bodyclass
// example of embedded logo, base64 encoded inline, No styling here
// const char HTTP_ROOT_MAIN[]        PROGMEM = "<img title=' alt=' src='data:image/png;base64,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' /><h1>{v}</h1><h3>WiFiManager</h3>";
const char HTTP_ROOT_MAIN[]        PROGMEM = "<h1>{t}</h1><h3>{v}</h3>";
const char * const HTTP_PORTAL_MENU[] PROGMEM = {
"<form action='/wifi'    method='get'><button>Configure WiFi</button></form><br/>\n", // MENU_WIFI
"<form action='/0wifi'   method='get'><button>Configure WiFi (No Scan)</button></form><br/>\n", // MENU_WIFINOSCAN
"<form action='/info'    method='get'><button>Info</button></form><br/>\n", // MENU_INFO
"<form action='/param'   method='get'><button>Setup</button></form><br/>\n",//MENU_PARAM
"<form action='/close'   method='get'><button>Close</button></form><br/>\n", // MENU_CLOSE
"<form action='/restart' method='get'><button>Restart</button></form><br/>\n",// MENU_RESTART
"<form action='/exit'    method='get'><button>Exit</button></form><br/>\n",  // MENU_EXIT
"<form action='/erase'   method='get'><button class='D'>Erase</button></form><br/>\n", // MENU_ERASE
"<form action='/update'  method='get'><button>Update</button></form><br/>\n",// MENU_UPDATE
"<hr><br/>" // MENU_SEP
};

// const char HTTP_PORTAL_OPTIONS[]   PROGMEM = strcat(HTTP_PORTAL_MENU[0] , HTTP_PORTAL_MENU[3] , HTTP_PORTAL_MENU[7]);
const char HTTP_PORTAL_OPTIONS[]   PROGMEM = "";
const char HTTP_ITEM_QI[]          PROGMEM = "<div role='img' aria-label='{r}%' title='{r}%' class='q q-{q} {i} {h}'></div>"; // rssi icons
const char HTTP_ITEM_QP[]          PROGMEM = "<div class='q {h}'>{r}%</div>"; // rssi percentage {h} = hidden showperc pref
const char HTTP_ITEM[]             PROGMEM = "<div><a href='#p' onclick='c(this)'>{v}</a>{qi}{qp}</div>"; // {q} = HTTP_ITEM_QI, {r} = HTTP_ITEM_QP
// const char HTTP_ITEM[]            PROGMEM = "<div><a href='#p' onclick='c(this)'>{v}</a> {R} {r}% {q} {e}</div>"; // test all tokens

const char HTTP_FORM_START[]       PROGMEM = "<form method='POST' action='{v}'>";
const char HTTP_FORM_WIFI[]        PROGMEM = "<label for='s'>SSID</label><input id='s' name='s' maxlength='32' autocorrect='off' autocapitalize='none' placeholder='{v}'><br/><label for='p'>Password</label><input id='p' name='p' maxlength='64' type='password' placeholder='{p}'>";
const char HTTP_FORM_WIFI_END[]    PROGMEM = "";
const char HTTP_FORM_STATIC_HEAD[] PROGMEM = "<hr><br/>";
const char HTTP_FORM_END[]         PROGMEM = "<br/><br/><button type='submit'>Save</button></form>";
const char HTTP_FORM_LABEL[]       PROGMEM = "<label for='{i}'>{t}</label>";
const char HTTP_FORM_PARAM_HEAD[]  PROGMEM = "<hr><br/>";
const char HTTP_FORM_PARAM[]       PROGMEM = "<br/><input id='{i}' name='{n}' maxlength='{l}' value='{v}' {c}>";

const char HTTP_SCAN_LINK[]        PROGMEM = "<br/><form action='/wifi?refresh=1' method='POST'><button name='refresh' value='1'>Refresh</button></form>";
const char HTTP_SAVED[]            PROGMEM = "<div class='msg'>Saving Credentials<br/>Trying to connect ESP to network.<br />If it fails reconnect to AP to try again</div>";
const char HTTP_PARAMSAVED[]       PROGMEM = "<div class='msg S'>Saved<br/></div>";
const char HTTP_END[]              PROGMEM = "</div></body></html>";
const char HTTP_ERASEBTN[]         PROGMEM = "<br/><form action='/erase' method='get'><button class='D'>Erase WiFi Config</button></form>";
const char HTTP_UPDATEBTN[]        PROGMEM = "<br/><form action='/update' method='get'><button>Update</button></form>";
const char HTTP_BACKBTN[]          PROGMEM = "<hr><br/><form action='/' method='get'><button>Back</button></form>";

const char HTTP_STATUS_ON[]        PROGMEM = "<div class='msg S'><strong>Connected</strong> to {v}<br/><em><small>with IP {i}</small></em></div>";
const char HTTP_STATUS_OFF[]       PROGMEM = "<div class='msg {c}'><strong>Not Connected</strong> to {v}{r}</div>"; // {c=class} {v=ssid} {r=status_off}
const char HTTP_STATUS_OFFPW[]     PROGMEM = "<br/>Authentication Failure"; // STATION_WRONG_PASSWORD,  no eps32
const char HTTP_STATUS_OFFNOAP[]   PROGMEM = "<br/>AP not found";   // WL_NO_SSID_AVAIL
const char HTTP_STATUS_OFFFAIL[]   PROGMEM = "<br/>Could not Connect"; // WL_CONNECT_FAILED
const char HTTP_STATUS_NONE[]      PROGMEM = "<div class='msg'>No AP set</div>";
const char HTTP_BR[]               PROGMEM = "<br/>";

const char HTTP_STYLE[]            PROGMEM = "<style>"
".c,body{text-align:center;font-family:verdana}div,input{padding:5px;font-size:1em;margin:5px 0;box-sizing:border-box;}"
"input,button,.msg{border-radius:.3rem;width: 100%},input[type=radio]{width: auto}"
"button,input[type='button'],input[type='submit']{cursor:pointer;border:0;background-color:#1fa3ec;color:#fff;line-height:2.4rem;font-size:1.2rem;width:100%}"
"input[type='file']{border:1px solid #1fa3ec}"
".wrap {text-align:left;display:inline-block;min-width:260px;max-width:500px}"
// links
"a{color:#000;font-weight:700;text-decoration:none}a:hover{color:#1fa3ec;text-decoration:underline}"
// quality icons
".q{height:16px;margin:0;padding:0 5px;text-align:right;min-width:38px;float:right}.q.q-0:after{background-position-x:0}.q.q-1:after{background-position-x:-16px}.q.q-2:after{background-position-x:-32px}.q.q-3:after{background-position-x:-48px}.q.q-4:after{background-position-x:-64px}.q.l:before{background-position-x:-80px;padding-right:5px}.ql .q{float:left}.q:after,.q:before{content:'';width:16px;height:16px;display:inline-block;background-repeat:no-repeat;background-position: 16px 0;"
"background-image:url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAGAAAAAQCAMAAADeZIrLAAAAJFBMVEX///8AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAADHJj5lAAAAC3RSTlMAIjN3iJmqu8zd7vF8pzcAAABsSURBVHja7Y1BCsAwCASNSVo3/v+/BUEiXnIoXkoX5jAQMxTHzK9cVSnvDxwD8bFx8PhZ9q8FmghXBhqA1faxk92PsxvRc2CCCFdhQCbRkLoAQ3q/wWUBqG35ZxtVzW4Ed6LngPyBU2CobdIDQ5oPWI5nCUwAAAAASUVORK5CYII=');}"
// icons @2x media query (32px rescaled)
"@media (-webkit-min-device-pixel-ratio: 2),(min-resolution: 192dpi){.q:before,.q:after {"
"background-image:url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAALwAAAAgCAMAAACfM+KhAAAALVBMVEX///8AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAADAOrOgAAAADnRSTlMAESIzRGZ3iJmqu8zd7gKjCLQAAACmSURBVHgB7dDBCoMwEEXRmKlVY3L//3NLhyzqIqSUggy8uxnhCR5Mo8xLt+14aZ7wwgsvvPA/ofv9+44334UXXngvb6XsFhO/VoC2RsSv9J7x8BnYLW+AjT56ud/uePMdb7IP8Bsc/e7h8Cfk912ghsNXWPpDC4hvN+D1560A1QPORyh84VKLjjdvfPFm++i9EWq0348XXnjhhT+4dIbCW+WjZim9AKk4UZMnnCEuAAAAAElFTkSuQmCC');"
"background-size: 95px 16px;}}"
// msg callouts
".msg{padding:20px;margin:20px 0;border:1px solid #eee;border-left-width:5px;border-left-color:#777}.msg h4{margin-top:0;margin-bottom:5px}.msg.P{border-left-color:#1fa3ec}.msg.P h4{color:#1fa3ec}.msg.D{border-left-color:#dc3630}.msg.D h4{color:#dc3630}.msg.S{border-left-color: #5cb85c}.msg.S h4{color: #5cb85c}"
// lists
"dt{font-weight:bold}dd{margin:0;padding:0 0 0.5em 0;min-height:12px}"
"td{vertical-align: top;}"
".h{display:none}"
"button.D{background-color:#dc3630}"
// invert
"body.invert,body.invert a,body.invert h1 {background-color:#060606;color:#fff;}"
"body.invert .msg{color:#fff;background-color:#282828;border-top:1px solid #555;border-right:1px solid #555;border-bottom:1px solid #555;}"
"body.invert .q[role=img]{-webkit-filter:invert(1);filter:invert(1);}"
"input:disabled {opacity: 0.5;}"
"</style>";

#ifndef WM_NOHELP
const char HTTP_HELP[]             PROGMEM =
 "<br/><h3>Available Pages</h3><hr>"
 "<table class='table'>"
 "<thead><tr><th>Page</th><th>Function</th></tr></thead><tbody>"
 "<tr><td><a href='/'>/</a></td>"
 "<td>Menu page.</td></tr>"
 "<tr><td><a href='/wifi'>/wifi</a></td>"
 "<td>Show WiFi scan results and enter WiFi configuration.(/0wifi noscan)</td></tr>"
 "<tr><td><a href='/wifisave'>/wifisave</a></td>"
 "<td>Save WiFi configuration information and configure device. Needs variables supplied.</td></tr>"
 "<tr><td><a href='/param'>/param</a></td>"
 "<td>Parameter page</td></tr>"
 "<tr><td><a href='/info'>/info</a></td>"
 "<td>Information page</td></tr>"
 "<tr><td><a href='/u'>/u</a></td>"
 "<td>OTA Update</td></tr>"
 "<tr><td><a href='/close'>/close</a></td>"
 "<td>Close the captiveportal popup,configportal will remain active</td></tr>"
 "<tr><td>/exit</td>"
 "<td>Exit Config Portal, configportal will close</td></tr>"
 "<tr><td>/restart</td>"
 "<td>Reboot the device</td></tr>"
 "<tr><td>/erase</td>"
 "<td>Erase WiFi configuration and reboot Device. Device will not reconnect to a network until new WiFi configuration data is entered.</td></tr>"
 "</table>"
 "<p/>More information about WiFiManager at <a href='https://github.com/tzapu/WiFiManager'>https://github.com/tzapu/WiFiManager</a>.";
#else
const char HTTP_HELP[]             PROGMEM = "";
#endif

const char HTTP_UPDATE[] PROGMEM = "Upload New Firmware<br/><form method='POST' action='u' enctype='multipart/form-data' onchange=\"(function(el){document.getElementById('uploadbin').style.display = el.value=='' ? 'none' : 'initial';})(this)\"><input type='file' name='update' accept='.bin,application/octet-stream'><button id='uploadbin' type='submit' class='h D'>Update</button></form><small><a href='http://192.168.4.1/update' target='_blank'>* May not function inside captive portal, Open in browser http://192.168.4.1</a><small>";
const char HTTP_UPDATE_FAIL[] PROGMEM = "<div class='msg D'><strong>Update Failed!</strong><Br/>Reboot device and try again</div>";
const char HTTP_UPDATE_SUCCESS[] PROGMEM = "<div class='msg S'><strong>Update Successful.  </strong> <br/> Device Rebooting now...</div>";

#ifdef WM_JSTEST
const char HTTP_JS[] PROGMEM = 
"<script>function postAjax(url, data, success) {"
"    var params = typeof data == 'string' ? data : Object.keys(data).map("
"            function(k){ return encodeURIComponent(k) + '=' + encodeURIComponent(data[k]) }"
"        ).join('&');"
"    var xhr = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject(\"Microsoft.XMLHTTP\");"
"    xhr.open('POST', url);"
"    xhr.onreadystatechange = function() {"
"        if (xhr.readyState>3 && xhr.status==200) { success(xhr.responseText); }"
"    };"
"    xhr.setRequestHeader('X-Requested-With', 'XMLHttpRequest');"
"    xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');"
"    xhr.send(params);"
"    return xhr;}"
"postAjax('/status', 'p1=1&p2=Hello+World', function(data){ console.log(data); });"
"postAjax('/status', { p1: 1, p2: 'Hello World' }, function(data){ console.log(data); });"
"</script>";
#endif

// Info html
#ifdef ESP32
	const char HTTP_INFO_esphead[]    PROGMEM = "<h3>esp32</h3><hr><dl>";
	const char HTTP_INFO_chiprev[]    PROGMEM = "<dt>Chip Rev</dt><dd>{1}</dd>";
  	const char HTTP_INFO_lastreset[]  PROGMEM = "<dt>Last reset reason</dt><dd>CPU0: {1}<br/>CPU1: {2}</dd>";
  	const char HTTP_INFO_aphost[]     PROGMEM = "<dt>Acccess Point Hostname</dt><dd>{1}</dd>";  
    const char HTTP_INFO_psrsize[]    PROGMEM = "<dt>PSRAM Size</dt><dd>{1} bytes</dd>";
	const char HTTP_INFO_temp[]       PROGMEM = "<dt>Temperature</dt><dd>{1} C&deg; / {2} F&deg;</dd><dt>Hall</dt><dd>{3}</dd>";    
#else
	const char HTTP_INFO_esphead[]    PROGMEM = "<h3>esp8266</h3><hr><dl>";
	const char HTTP_INFO_fchipid[]    PROGMEM = "<dt>Flash Chip ID</dt><dd>{1}</dd>";
	const char HTTP_INFO_corever[]    PROGMEM = "<dt>Core Version</dt><dd>{1}</dd>";
	const char HTTP_INFO_bootver[]    PROGMEM = "<dt>Boot Version</dt><dd>{1}</dd>";
	const char HTTP_INFO_lastreset[]  PROGMEM = "<dt>Last reset reason</dt><dd>{1}</dd>";
	const char HTTP_INFO_flashsize[]  PROGMEM = "<dt>Real Flash Size</dt><dd>{1} bytes</dd>";
#endif

const char HTTP_INFO_memsmeter[]  PROGMEM = "<br/><progress value='{1}' max='{2}'></progress></dd>";
const char HTTP_INFO_memsketch[]  PROGMEM = "<dt>Memory - Sketch Size</dt><dd>Used / Total bytes<br/>{1} / {2}";
const char HTTP_INFO_freeheap[]   PROGMEM = "<dt>Memory - Free Heap</dt><dd>{1} bytes available</dd>"; 
const char HTTP_INFO_wifihead[]   PROGMEM = "<br/><h3>WiFi</h3><hr>";
const char HTTP_INFO_uptime[]     PROGMEM = "<dt>Uptime</dt><dd>{1} Mins {2} Secs</dd>";
const char HTTP_INFO_chipid[]     PROGMEM = "<dt>Chip ID</dt><dd>{1}</dd>";
const char HTTP_INFO_idesize[]    PROGMEM = "<dt>Flash Size</dt><dd>{1} bytes</dd>";
const char HTTP_INFO_sdkver[]     PROGMEM = "<dt>SDK Version</dt><dd>{1}</dd>";
const char HTTP_INFO_cpufreq[]    PROGMEM = "<dt>CPU Frequency</dt><dd>{1}MHz</dd>";
const char HTTP_INFO_apip[]       PROGMEM = "<dt>Access Point IP</dt><dd>{1}</dd>";
const char HTTP_INFO_apmac[]      PROGMEM = "<dt>Access Point MAC</dt><dd>{1}</dd>";
const char HTTP_INFO_apssid[]     PROGMEM = "<dt>Access Point SSID</dt><dd>{1}</dd>";
const char HTTP_INFO_apbssid[]    PROGMEM = "<dt>BSSID</dt><dd>{1}</dd>";
const char HTTP_INFO_stassid[]    PROGMEM = "<dt>Station SSID</dt><dd>{1}</dd>";
const char HTTP_INFO_staip[]      PROGMEM = "<dt>Station IP</dt><dd>{1}</dd>";
const char HTTP_INFO_stagw[]      PROGMEM = "<dt>Station Gateway</dt><dd>{1}</dd>";
const char HTTP_INFO_stasub[]     PROGMEM = "<dt>Station Subnet</dt><dd>{1}</dd>";
const char HTTP_INFO_dnss[]       PROGMEM = "<dt>DNS Server</dt><dd>{1}</dd>";
const char HTTP_INFO_host[]       PROGMEM = "<dt>Hostname</dt><dd>{1}</dd>";
const char HTTP_INFO_stamac[]     PROGMEM = "<dt>Station MAC</dt><dd>{1}</dd>";
const char HTTP_INFO_conx[]       PROGMEM = "<dt>Connected</dt><dd>{1}</dd>";
const char HTTP_INFO_autoconx[]   PROGMEM = "<dt>Autoconnect</dt><dd>{1}</dd>";


const char S_brand[]              PROGMEM = "WiFiManager";
const char S_debugPrefix[]        PROGMEM = "*wm:";
const char S_y[]                  PROGMEM = "Yes";
const char S_n[]                  PROGMEM = "No";
const char S_enable[]             PROGMEM = "Enabled";
const char S_disable[]            PROGMEM = "Disabled";
const char S_GET[]                PROGMEM = "GET";
const char S_POST[]               PROGMEM = "POST";
const char S_NA[]                 PROGMEM = "Unknown";
const char S_passph[]             PROGMEM = "********";
const char S_titlewifisaved[]     PROGMEM = "Credentials Saved";
const char S_titlewifisettings[]  PROGMEM = "Settings Saved";
const char S_titlewifi[]          PROGMEM = "Config ESP";
const char S_titleinfo[]          PROGMEM = "Info";
const char S_titleparam[]         PROGMEM = "Setup";
const char S_titleparamsaved[]    PROGMEM = "Setup Saved";
const char S_titleexit[]          PROGMEM = "Exit";
const char S_titlereset[]         PROGMEM = "Reset";
const char S_titleerase[]         PROGMEM = "Erase";
const char S_titleclose[]         PROGMEM = "Close";
const char S_options[]            PROGMEM = "options";
const char S_nonetworks[]         PROGMEM = "No networks found. Refresh to scan again.";
const char S_staticip[]           PROGMEM = "Static IP";
const char S_staticgw[]           PROGMEM = "Static Gateway";
const char S_staticdns[]          PROGMEM = "Static DNS";
const char S_subnet[]             PROGMEM = "Subnet";
const char S_exiting[]            PROGMEM = "Exiting";
const char S_resetting[]          PROGMEM = "Module will reset in a few seconds.";
const char S_closing[]            PROGMEM = "You can close the page, portal will continue to run";
const char S_error[]              PROGMEM = "An Error Occured";
const char S_notfound[]           PROGMEM = "File Not Found\n\n";
const char S_uri[]                PROGMEM = "URI: ";
const char S_method[]             PROGMEM = "\nMethod: ";
const char S_args[]               PROGMEM = "\nArguments: ";
const char S_parampre[]           PROGMEM = "param_";

// debug strings
const char D_HR[]                 PROGMEM = "--------------------";

// END WIFI_MANAGER_OVERRIDE_STRINGS
#endif

// -----------------------------------------------------------------------------------------------
// DO NOT EDIT BELOW THIS LINE

const uint8_t _nummenutokens = 10;
const char * const _menutokens[10] PROGMEM = {
    "wifi",
    "wifinoscan",
    "info",
    "param",
    "close",
    "restart",
    "exit",
    "erase",
    "update",
    "sep"
};

const char R_root[]               PROGMEM = "/";
const char R_wifi[]               PROGMEM = "/wifi";
const char R_wifinoscan[]         PROGMEM = "/0wifi";
const char R_wifisave[]           PROGMEM = "/wifisave";
const char R_info[]               PROGMEM = "/info";
const char R_param[]              PROGMEM = "/param";
const char R_paramsave[]          PROGMEM = "/paramsave";
const char R_restart[]            PROGMEM = "/restart";
const char R_exit[]               PROGMEM = "/exit";
const char R_close[]              PROGMEM = "/close";
const char R_erase[]              PROGMEM = "/erase"; 
const char R_status[]             PROGMEM = "/status";
const char R_update[]             PROGMEM = "/update";
const char R_updatedone[]         PROGMEM = "/u";


//Strings
const char S_ip[]                 PROGMEM = "ip";
const char S_gw[]                 PROGMEM = "gw";
const char S_sn[]                 PROGMEM = "sn";
const char S_dns[]                PROGMEM = "dns";

// softap ssid default prefix
#ifdef ESP8266
	const char S_ssidpre[]        PROGMEM = "ESP";
#elif defined(ESP32)
	const char S_ssidpre[]        PROGMEM = "ESP32";
#else
	const char S_ssidpre[]        PROGMEM = "WM";
#endif

//Tokens
//@todo consolidate and reduce
const char T_ss[]                 PROGMEM = "{"; // token start sentinel
const char T_es[]                 PROGMEM = "}"; // token end sentinel
const char T_1[]                  PROGMEM = "{1}"; // @token 1
const char T_2[]                  PROGMEM = "{2}"; // @token 2
const char T_3[]                  PROGMEM = "{3}"; // @token 2
const char T_v[]                  PROGMEM = "{v}"; // @token v
const char T_I[]                  PROGMEM = "{I}"; // @token I
const char T_i[]                  PROGMEM = "{i}"; // @token i
const char T_n[]                  PROGMEM = "{n}"; // @token n
const char T_p[]                  PROGMEM = "{p}"; // @token p
const char T_t[]                  PROGMEM = "{t}"; // @token t
const char T_l[]                  PROGMEM = "{l}"; // @token l
const char T_c[]                  PROGMEM = "{c}"; // @token c
const char T_e[]                  PROGMEM = "{e}"; // @token e
const char T_q[]                  PROGMEM = "{q}"; // @token q
const char T_r[]                  PROGMEM = "{r}"; // @token r
const char T_R[]                  PROGMEM = "{R}"; // @token R
const char T_h[]                  PROGMEM = "{h}"; // @token h

// http
const char HTTP_HEAD_CL[]         PROGMEM = "Content-Length";
const char HTTP_HEAD_CT[]         PROGMEM = "text/html";
const char HTTP_HEAD_CT2[]        PROGMEM = "text/plain";
const char HTTP_HEAD_CORS[]       PROGMEM = "Access-Control-Allow-Origin";
const char HTTP_HEAD_CORS_ALLOW_ALL[]  PROGMEM = "*";

const char * const WIFI_STA_STATUS[] PROGMEM
{
  "WL_IDLE_STATUS",     // 0 STATION_IDLE
  "WL_NO_SSID_AVAIL",   // 1 STATION_NO_AP_FOUND
  "WL_SCAN_COMPLETED",  // 2
  "WL_CONNECTED",       // 3 STATION_GOT_IP
  "WL_CONNECT_FAILED",  // 4 STATION_CONNECT_FAIL, STATION_WRONG_PASSWORD(NI)
  "WL_CONNECTION_LOST", // 5
  "WL_DISCONNECTED",    // 6 
  "WL_STATION_WRONG_PASSWORD" // 7 KLUDGE 
};

#ifdef ESP32
const char * const AUTH_MODE_NAMES[] PROGMEM
{
    "OPEN",
    "WEP",             
    "WPA_PSK",         
    "WPA2_PSK",        
    "WPA_WPA2_PSK",    
    "WPA2_ENTERPRISE", 
    "MAX"
};
#elif defined(ESP8266)
const char * const AUTH_MODE_NAMES[] PROGMEM
{
    "",
    "",
    "WPA_PSK",      // 2 ENC_TYPE_TKIP
    "",
    "WPA2_PSK",     // 4 ENC_TYPE_CCMP
    "WEP",          // 5 ENC_TYPE_WEP
    "",
    "OPEN",         //7 ENC_TYPE_NONE
    "WPA_WPA2_PSK", // 8 ENC_TYPE_AUTO
};
#endif

const char* const WIFI_MODES[] PROGMEM = { "NULL", "STA", "AP", "STA+AP" };


#ifdef ESP32
// as 2.5.2
// typedef struct {
//     char                  cc[3];   /**< country code string */
//     uint8_t               schan;   /**< start channel */
//     uint8_t               nchan;   /**< total channel number */
//     int8_t                max_tx_power;   /**< This field is used for getting WiFi maximum transmitting power, call esp_wifi_set_max_tx_power to set the maximum transmitting power. */
//     wifi_country_policy_t policy;  /**< country policy */
// } wifi_country_t;
const wifi_country_t WM_COUNTRY_US{"US",1,11,CONFIG_ESP32_PHY_MAX_TX_POWER,WIFI_COUNTRY_POLICY_AUTO};
const wifi_country_t WM_COUNTRY_CN{"CN",1,13,CONFIG_ESP32_PHY_MAX_TX_POWER,WIFI_COUNTRY_POLICY_AUTO};
const wifi_country_t WM_COUNTRY_JP{"JP",1,14,CONFIG_ESP32_PHY_MAX_TX_POWER,WIFI_COUNTRY_POLICY_AUTO};
#elif defined(ESP8266) && !defined(WM_NOCOUNTRY)
// typedef struct {
//     char cc[3];               /**< country code string */
//     uint8_t schan;            /**< start channel */
//     uint8_t nchan;            /**< total channel number */
//     uint8_t policy;           /**< country policy */
// } wifi_country_t;
const wifi_country_t WM_COUNTRY_US{"US",1,11,WIFI_COUNTRY_POLICY_AUTO};
const wifi_country_t WM_COUNTRY_CN{"CN",1,13,WIFI_COUNTRY_POLICY_AUTO};
const wifi_country_t WM_COUNTRY_JP{"JP",1,14,WIFI_COUNTRY_POLICY_AUTO};
#endif


/*
* ESP32 WiFi Events

0  SYSTEM_EVENT_WIFI_READY               < ESP32 WiFi ready
1  SYSTEM_EVENT_SCAN_DONE                < ESP32 finish scanning AP
2  SYSTEM_EVENT_STA_START                < ESP32 station start
3  SYSTEM_EVENT_STA_STOP                 < ESP32 station stop
4  SYSTEM_EVENT_STA_CONNECTED            < ESP32 station connected to AP
5  SYSTEM_EVENT_STA_DISCONNECTED         < ESP32 station disconnected from AP
6  SYSTEM_EVENT_STA_AUTHMODE_CHANGE      < the auth mode of AP connected by ESP32 station changed
7  SYSTEM_EVENT_STA_GOT_IP               < ESP32 station got IP from connected AP
8  SYSTEM_EVENT_STA_LOST_IP              < ESP32 station lost IP and the IP is reset to 0
9  SYSTEM_EVENT_STA_WPS_ER_SUCCESS       < ESP32 station wps succeeds in enrollee mode
10 SYSTEM_EVENT_STA_WPS_ER_FAILED        < ESP32 station wps fails in enrollee mode
11 SYSTEM_EVENT_STA_WPS_ER_TIMEOUT       < ESP32 station wps timeout in enrollee mode
12 SYSTEM_EVENT_STA_WPS_ER_PIN           < ESP32 station wps pin code in enrollee mode
13 SYSTEM_EVENT_AP_START                 < ESP32 soft-AP start
14 SYSTEM_EVENT_AP_STOP                  < ESP32 soft-AP stop
15 SYSTEM_EVENT_AP_STACONNECTED          < a station connected to ESP32 soft-AP
16 SYSTEM_EVENT_AP_STADISCONNECTED       < a station disconnected from ESP32 soft-AP
17 SYSTEM_EVENT_AP_STAIPASSIGNED         < ESP32 soft-AP assign an IP to a connected station
18 SYSTEM_EVENT_AP_PROBEREQRECVED        < Receive probe request packet in soft-AP interface
19 SYSTEM_EVENT_GOT_IP6                  < ESP32 station or ap or ethernet interface v6IP addr is preferred
20 SYSTEM_EVENT_ETH_START                < ESP32 ethernet start
21 SYSTEM_EVENT_ETH_STOP                 < ESP32 ethernet stop
22 SYSTEM_EVENT_ETH_CONNECTED            < ESP32 ethernet phy link up
23 SYSTEM_EVENT_ETH_DISCONNECTED         < ESP32 ethernet phy link down
24 SYSTEM_EVENT_ETH_GOT_IP               < ESP32 ethernet got IP from connected AP
25 SYSTEM_EVENT_MAX


typedef enum {
    ARDUINO_EVENT_WIFI_READY = 0,
    ARDUINO_EVENT_WIFI_SCAN_DONE,
    ARDUINO_EVENT_WIFI_STA_START,
    ARDUINO_EVENT_WIFI_STA_STOP,
    ARDUINO_EVENT_WIFI_STA_CONNECTED,
    ARDUINO_EVENT_WIFI_STA_DISCONNECTED,
    ARDUINO_EVENT_WIFI_STA_AUTHMODE_CHANGE,
    ARDUINO_EVENT_WIFI_STA_GOT_IP,
    ARDUINO_EVENT_WIFI_STA_GOT_IP6,
    ARDUINO_EVENT_WIFI_STA_LOST_IP,
    ARDUINO_EVENT_WIFI_AP_START,
    ARDUINO_EVENT_WIFI_AP_STOP,
    ARDUINO_EVENT_WIFI_AP_STACONNECTED,
    ARDUINO_EVENT_WIFI_AP_STADISCONNECTED,
    ARDUINO_EVENT_WIFI_AP_STAIPASSIGNED,
    ARDUINO_EVENT_WIFI_AP_PROBEREQRECVED,
    ARDUINO_EVENT_WIFI_AP_GOT_IP6,
    ARDUINO_EVENT_WIFI_FTM_REPORT,
    ARDUINO_EVENT_ETH_START,
    ARDUINO_EVENT_ETH_STOP,
    ARDUINO_EVENT_ETH_CONNECTED,
    ARDUINO_EVENT_ETH_DISCONNECTED,
    ARDUINO_EVENT_ETH_GOT_IP,
    ARDUINO_EVENT_ETH_GOT_IP6,
    ARDUINO_EVENT_WPS_ER_SUCCESS,
    ARDUINO_EVENT_WPS_ER_FAILED,
    ARDUINO_EVENT_WPS_ER_TIMEOUT,
    ARDUINO_EVENT_WPS_ER_PIN,
    ARDUINO_EVENT_WPS_ER_PBC_OVERLAP,
    ARDUINO_EVENT_SC_SCAN_DONE,
    ARDUINO_EVENT_SC_FOUND_CHANNEL,
    ARDUINO_EVENT_SC_GOT_SSID_PSWD,
    ARDUINO_EVENT_SC_SEND_ACK_DONE,
    ARDUINO_EVENT_PROV_INIT,
    ARDUINO_EVENT_PROV_DEINIT,
    ARDUINO_EVENT_PROV_START,
    ARDUINO_EVENT_PROV_END,
    ARDUINO_EVENT_PROV_CRED_RECV,
    ARDUINO_EVENT_PROV_CRED_FAIL,
    ARDUINO_EVENT_PROV_CRED_SUCCESS,
    ARDUINO_EVENT_MAX
} arduino_event_id_t;

typedef union {
    wifi_event_sta_scan_done_t wifi_scan_done;
    wifi_event_sta_authmode_change_t wifi_sta_authmode_change;
    wifi_event_sta_connected_t wifi_sta_connected;
    wifi_event_sta_disconnected_t wifi_sta_disconnected;
    wifi_event_sta_wps_er_pin_t wps_er_pin;
    wifi_event_sta_wps_fail_reason_t wps_fail_reason;
    wifi_event_ap_probe_req_rx_t wifi_ap_probereqrecved;
    wifi_event_ap_staconnected_t wifi_ap_staconnected;
    wifi_event_ap_stadisconnected_t wifi_ap_stadisconnected;
    wifi_event_ftm_report_t wifi_ftm_report;
    ip_event_ap_staipassigned_t wifi_ap_staipassigned;
    ip_event_got_ip_t got_ip;
    ip_event_got_ip6_t got_ip6;
    smartconfig_event_got_ssid_pswd_t sc_got_ssid_pswd;
    esp_eth_handle_t eth_connected;
    wifi_sta_config_t prov_cred_recv;
    wifi_prov_sta_fail_reason_t prov_fail_reason;
} arduino_event_info_t;

*/
#endif

definitions for the parameter (the options are listed in the html):

const char htmlAlarmLEDsComboBox[htmlAlarmLEDsComboBoxLength] PROGMEM = "<label for='ledalarmefect'>LEDs alarm effect</label><br/><select name='ledalarmefect' id='ledalarmefect'><option value='0'>none</option><option value='1'>Sunrise</option><option value='2'>Blink</option><option value='3'>Cycle</option><option value='4'>Pulse</option></select><script>document.getElementById('ledalarmefect').selectedIndex = %d;</script>";

char alarmLEDsComboBoxHtml[htmlAlarmLEDsComboBoxLength];
WiFiManagerParameter wmParamAlarmLEDs(alarmLEDsComboBoxHtml);

setting html and initial value into parameter in setup()

sprintf_P(alarmLEDsComboBoxHtml, htmlAlarmLEDsComboBox, (int) config.alarmLEDs);
wm.addParameter(&wmParamAlarmLEDs);

getting the value in the save callback and setting it to html again:

  String s = wm.server->arg("ledalarmefect");
  config.alarmLEDs = (AlarmLEDs) s.toInt();
  sprintf_P(alarmLEDsComboBoxHtml, htmlAlarmLEDsComboBox, (int) config.alarmLEDs);

if your options are dynamic, you can build the html in code

Hi Juraj,

I appreciate your help and code but I am clearly at a level far below yourself.
Completely lost with what you sent through, is it some sort of clock? Wouldn't compile for me...

Without complicating things this is what I am trying to do:

On the WiFi Setup page have a dropdown box

Label = "Select Currency:"
Options = "BTC,XLM,ATLAS"
Values = "btc-api-url,xlm-api-url,atlas-api-url"

When selected and saved, variable 'Currency=value' is saved to eeprom
Then in main code (after a reboot & connection to network specified in setup) be able to use the variable 'Currency' ie the api url of the currency chosen at setup.

What is what you don't understand from my previous comment? I can explain the details

My suggestion did not involve modifying any library.

Hi,
My programming is limited so don't understand a lot of what you supplied, sorry...
Can you explain what would need to be done to achieve:

On the WiFi Setup page have a dropdown box

Label = "Select Currency:"
Options = "BTC,XLM,ATLAS"
Values = "btc-api-url,xlm-api-url,atlas-api-url"

When selected and saved, variable 'Currency=value' is saved to eeprom
Then in main code (after a reboot & connection to network specified in setup) be able to use the variable 'Currency' ie the api url of the currency chosen at setup.

sorry, I misunderstood your post. I thought you already have the custom parameter as field and now you search for a solution how to make it as dropdownlist, because dropdownlist is not directly supported by the WiFiManager library.
For basic custom parameters see the examples of the WiFiManager library.